An interleave-division multiple-access (IDMA) is a multiple-access manner adapted to differentiate different subscribers by using a chip-level interleaving method.
A key point of the FDMA technology is to assign different interleavers for the different subscribers. Recently, there are mainly two methods for designing the interleavers for the different subscribers in the IDMA system.
In a first method, the IDMA system requires that a spreading chip interleaver of each subscriber may be different, and thus one simplest and most direct method is to design a different chip interleaver for each subscriber, in which each interleaver is randomly generated.
In a technical solution of the first method, the interleaver may be separately designed for each subscriber. Further, in order to finish interleaving and de-interleaving processes of all the spreading chips of different subscribers, information of the interleaver and the de-interleaver of each subscriber may be stored in the system. When the lengths of the interleaver and the de-interleaver are relatively long, and the number of the subscribers is large, storage of the information of the interleavers and the de-interleavers of all the subscribers may occupy a large portion of memory space, thereby increasing complexity of the system.
In a second method, one interleaver π and one de-interleaver π−1 are designed for the system first, the interleaver and the de-interleaver of a first subscriber are respectively π and π−1, the interleaver and the de-interleaver of a second subscriber are respectively 2 series π and 2 series π−1, and so forth, the interleaver and the de-interleaver of a kth subscriber are respectively k series π and k series π−1. The interleaver and the de-interleaver of the kth subscriber are as shown in FIG. 1.
In the technical solution of the second method, only the information of the interleaver π and the de-interleaver π−1 may be stored in the system, so as to obtain the information of the interleavers and the de-interleavers of all the subscribers.
The technical solution of the second method solves a problem of the first technical solution that the storage of the information of the interleavers and the de-interleavers of all the subscribers occupies a large portion of the memory space. However, in this technical solution, a spreading code word of the kth subscriber needs to finish the interleaving process through k series interleavers, and similarly, a code word received by the receiving end also needs to finish the de-interleaving process through k series de-interleavers, so that a time delay resulted during the code word interleaving and de-interleaving processes is much large. Moreover, the larger the number of the series interleavers is, the larger the time delay may be. The design manner of the interleavers in the second method requires a relatively high information process capability of the system, thereby increasing the complexity of the system.
In wireless communication systems, the application of the interleavers and the de-interleavers are very broad. When a plurality of different interleavers and de-interleavers are required to be designed for a transmitting end and a receiving end in the wireless communication system, the method adopted is basically the same as the above-mentioned method, except that in the IDMA system, the different interleavers and de-interleavers are adapted to differentiate the subscribers, and in other systems, the interleavers and the de-interleavers may not be adapted to differentiate the subscribers. The methods for designing the interleavers and the de-interleavers arc substantially the same, so the disadvantages of the first method one or the second method still exist in other wireless communication systems.